Recently, in corporation with the improvements of the graininess, the sharpness, and the color reproducibility of silver halide photographic materials such as mainly silver halide color negative photographic materials and with the popularization of a camera equipped with a zoom lens or a two focal points lens, high quality photographs enriched with variety have been obtained.
However, a camera equipped with a zoom lens or a two focal points lens, if the focal length at the telephoto side is lengthened, is quite large and consequently inconvenient to carry, while if the camera is small, it loses sufficient telephoto effect.
As a means for solving the aforesaid problems, a pseudo zoom technique has been recently proposed with the aid of the progress of the performance of color negative films as disclosed in U.S. Pat. Nos. 3,490,844, 4,583,831, and 4,650,304.
According to the pseudo zoom technique, information as to the focal distance of a lens inlet at the time of photographing is detected during the printing process to enlarge a part of the picture of the negative film, resulting in a telephoto effect for the developed print. The techniques of pseudo zoom hitherto proposed are for a color negative roll film of 135 format, which is a leading format at present.
However, it has been found that, when the aforesaid pseudo zoom technique is practiced using a color negative roll film of a 135 format, which is predominantly used at present, the image quality, particularly the sharpness of color images, is insufficient. Differing from a usual large-size print, the print obtained by the pseudo zoom technique corresponds to a small-size print cut from a part of a large-size print. The appreciation distance for a small-size print is shorter than that for a large-size print. Accordingly, in a small-size print formed by a pseudo zoom, the sharpness is very important.
The telephoto photographic print formed by a pseudo zoom corresponds to a print formed from a photographic film of a small format such as 110 format. However, in a 110 format, a cause of deteriorating the sharpness of the print is that the camera does not have a film pressure plate for securing the flatness of the film, and a shade paper at the back side of the film disturbs the flatness of the film.
However, it has also been found that the proposed pseudo zoom system does not have the aforesaid factors which deteriorate the sharpness of prints and, thus, the sharpness of the photographic film itself becomes very important for obtaining the print of sharp images in the pseudo zoom technique.
As a result of various investigations, the inventor has found that, when the humidity changes at photographing, film curls and thereby moves out of the focal plane of the camera and, in particular, in a print having a telephoto effect given by a pseudo zoom technique, the deterioration of the sharpness becomes severe. Furthermore, it has also been found that the use of a conventional cartridge (Patrone) for a 135 format which has been practically used with satisfactory results for the past several tens of years gives more serious reduction in the sharpness with changes in the humidity in the pseudo zoom technique.
The body portion of a cartridge for 135 format is cylindrical as shown in FIG. 1, the length of the outlet of film (port portion) of the cartridge is not constant, and the position of the cartridge in a camera is determined by the portion of a pile-like ribbon protruded from the port portion. Thus, when a cartridge is loaded in a camera, the position of the cartridge in the camera can not be controlled at a definite position.
Accordingly, in a combination of a 135 cartridge and a camera having a function of detecting the sensitivity of film by a general DX code, when the cartridge is loaded in the camera, it is impossible to keep the film outlet of the cartridge at the plane including the exposure stage of the camera, and, when the cartridge is once loaded in the camera, photographing is conducted in the non-plane state. If the film outlet of a cartridge is largely out of the plane of the exposure state of the camera, the extruded film near the film outlet is set in the camera in a bent state. It has been found that, when the bent film is sent to the exposure stage of the camera, the change of the curling state of the film in the exposure state is accelerated when humidity is changed to greatly deteriorate the flatness of the film. In particular, in a pseudo zoom print system, the enlarging magnification is increased and hence the inferiority of the flatness of film as described above becomes a serious defect. Therefore, it has been found that the establishment of the technique for stably keeping the flatness of film in the exposure stage of a camera is a new theme for improving the image quality of a print obtained by a pseudo zoom print system.
Furthermore, it has also been found that a serious problem caused by the increase of the enlarging magnification in a pseudo zoom print system is the scratches on the back surface of the film. As the result of various investigations, it has been confirmed that the scratches on the back surface of the film form white colorless portions on the print obtained therefrom, which are very conspicuous, and that more than 50% of the all of scratches of the film may form such white portions on the print. Accordingly, it has further been found that the prevention of the scratches on the back surface of a film is another new theme for improving the image quality of the print obtained by a pseudo zoom print system.